The use of elastomeric materials for obtaining dental impressions is well known in the art. Dental impressions are useful for providing detail of a patient's dental anatomy for the creation of inlays, onlays, full crowns and bridges, as well as removable prosthetic devices. Typically, the materials used to obtain dental impressions comprise two components. A low viscosity material is generally applied directly to the teeth, using for example, a syringe, and a separate higher viscosity material is placed into a dental tray for subsequent application to the teeth by inserting the tray into the patient's mouth and having the patient bite onto the tray. To obtain an optimum impression, it is important that the low viscosity material exhibit sufficient flowability to conform to the detail of the patient's dental anatomy while having sufficient viscosity to avoid spillage of the material off of the teeth and into the patient's mouth.
Prior methods of supplying and applying dental impression material have several drawbacks. According to one conventional method, impression materials are provided in separate containers to be measured and mixed by hand. The high viscosity and low viscosity materials are separately prepared and applied to the patient's teeth. This method of providing dental impression material is very time consuming and is prone to inaccurate mixing and/or measuring of the component materials, as well as exposure of the materials to contamination.
U.S. Pat. No. 4,995,540 to Colin et al. discloses a unit dosage dispenser for dental impression materials wherein the high and low viscosity materials are dispensed from a syringe-type device. The materials are provided in such a way that the low viscosity material is dispensed from the device first, followed by the high viscosity material. While this device addresses some concerns associated with the hand mixing of dental impression materials, it suffers drawbacks related to the timing of dispensing and applying the high and low viscosity materials from the device. For example, because the materials are contained in a common dispenser, they must be dispensed relatively contemporaneously with one another. The temporal dependence of dispensing the two materials may create problems when the set time or work time of the materials are not closely matched. Moreover, all of the low viscosity material must be dispensed before the high viscosity material may be applied to a dental tray.
There is thus a need for a dental impression material delivery system which overcomes drawbacks of the prior art, such as those described above.